Anodized aluminum alloy product



United States Patent 3,388,050 ANGDlZED ALUMINUM ALLOY PRODUCT EugeneWainer, Shaker Heights, Ohio, assignor to Horizons incorporated, acorporation of New Jersey No Drawing. Filed Sept. 7, 1965, Ser. No.485,630 6 Claims. (Cl. 20458) This invention relates to anodizedmaterials having a semi-porcelain finish and a pleasing appearance whichrenders them suitable as architectural materials, e.g. as buildingpanels.

More particularly, it relates to the products obtained when articleshaving surfaces consisting of aluminum alloys containing between 1 and4% of a metal selected from the group consisting of Ti, Zr, Nb, Ta andTh as essential constituents and between 0.01 and 0.1% of a metalselected from the group consisting of Ag, Au, Pd and Pt as an opticalconstituent are anodized and then sealed in the usual way. The anodized,sealed products of this invention are characterized by a semi-whiteporcelain like finish which is suitable, before sealing, for thereception of decorative or other impregnants.

The alloys to which the invention applies are obtained by inductionmelting suitable starting materials, e.g. ingot aluminum and a binarymaster alloy of aluminum containing about 50% of the desired alloyingelement and then after the melt has reached the proper fluidity anduniformity, casting it into shapes suitable for working to the desiredstructural product such as sheet or plate.

To achieve the desired finish it is preferred to anodize the articlesafter they have been cleaned and degreased by conventional techniquesusing one of the following:

(1) A 1% sulfuric acid electrolyte, prepared by adding 1 gram of 98%sulfuric acid to 99 cc. of water, is utilized at a temperature of 50 C.,a voltage of 20 to 25 volts, a current density of about 16 to 18 amperesper square foot for about 20 to 30 minutes.

(2) An oxalic solution containing 3 to 5 percent oxalic acid by weightand optionally up to 3% of a sodium or potassium oxalate, utilized at atemperature of 50 to 55 C. for about 30 minutes, at a voltage of 40 to50 volts and a current density of to amperes per square foot.

(3) An oxalic acid electrolyte as in 2 and containing 2 to 4 percent ofan alkali metal double oxalate of Ti, Zr or Th, operated at to 30amperes per square foot, about 120 volts, and at a temperature of 50 C.for 20 to 40 minutes, the pH being kept between 1.6 and 3.0.

(4) An oxalic acid electrolyte as in 2 and containing 2 to 4 percent ofat least one oxalate from the group tantalum hydrogen oxalate andniobium hydrogen oxalate 3,388,050 Patented June 11, 1968 "ice andoptionally 2 to 4 percent of an alkali metal double oxalate of Ti, Zr orTh, operated at about 50-55 C. at 40 to volt and 14 to 16 amperes persquare foot for about 30 minutes.

The anodizing processes are carried out in the usual manner described inmany patents and in the text Finishing of Aluminum by S. Wernick and R.Pinner published 1959 in England, but the invention resides in theanodizing of the specific aluminum base alloy described above to obtaina novel product not heretofore available.

Preferably sealing of the anodized surface is accom" plished in aboiling solution containing 0.5% nickel acetate, 0.5% cobalt acetate and1% boric acid, or in any other convenient sealing composition.

I claim:

1. Aluminum articles having at least one anodized surface formed of analloy consisting essentially of between 1% and 4% of metal selected fromthe group consisting of Ti, Zr, Nb, Ta and Th; between 0.01 and 0.1% ofa metal selected from the group consisting of Tg, A-u, Pd, and Pt; andthe balance substantially all Al.

2. Aluminum articles as in claim 1 which have been anodized in a 1%sulfuric acid electrolyte.

3. Aluminum articles as in claim 1 which have been anodized in an oxalicacid electrolyte.

4. Aluminum articles as in claim 1 which have been anodized in anelectrolyte comprising oxalic acid and at least one additional oxalate.

5. Aluminum articles as in claim 1 which have been anodized in anelectrolyte containing tantalum hydrogen oxalate.

6. Aluminum articles as in claim 1 which have been anodized in anelectrolyte containing niobium hydrogen oxalate.

References Cited UNITED STATES PATENTS 1,912,382 6/1933 Nock 1381,946,150 2/1934 Tosterud 20458 XR 2,050,587 8/1936 Ruben 75-138 XR2,056,604 10/1936 Guertler 75138 2,231,373 2/1941 Schenk 20458 XR2,260,278 10/1941 Schenk 20458 2,262,967 11/ 1941 Schenk 20458 2,272,7792/1942 Sarbey 75138 XR 2,798,037 7/1957 Robinson 20458 XR 2,966,7351/1961 Towner et al 75138 XR 2,966,736 1/1961 Towner et a1 75138 XR JOHNH. MACK, Primary Examiner.

G. KAPLAN, Assistant Examiner.

1. ALUMINUM ARTICLES HAVING AT LEAST ONE ANODIZED SURFACE FORMED OF ANALLOY CONSISTING ESSENTIALLY OF BETWEEN 1% AND 4% OF METAL SELECTED FROMTHE GROUP CONSISTING OF TI, ZR, NB, TA AD TH; BETWEEN 0.01 AND 0.1% OF AMETAL SELECTED FROM THE GROUP CONSISTING OF TG, AU, PD, AND PT; AND THEBALANCE SUBSTANTIALLY ALL AL.